1. Field of the Invention
This invention relates generally to drilling equipment used particularly in the hydrocarbon production industry and specifically to a method and apparatus for mechanized coupling and locking of bails to elevator ears and the concomitant coupling of power and control circuits between the bails and the suspended elevator.
2. Description of the Prior Art
In the hydrocarbon production industry, tubular goods, including drill strings, casings and tubing and often referred to simply as tubulars, must at varying stages be run, i.e. lowered, into or raised from a well. Elevators are devices which support the tubular for the purpose of raising or lowing it. An elevator may clamp along the side of a tubular using slips and dies to exert a radial clamping force on the tubular wall, or an elevator may use a bushing to support the tubular at the lower lip of a box connector. The latter method is preferable for deep water production as a slip can exert damaging crushing forces on the tubular under high hook loads.
FIGS. 1 and 2 show one typical elevator setup of prior art where an elevator (10) is suspended from a top drive mechanism (9) by a pair of bails, or links (14), which have eyes (16, 18) at both ends. The top drive mechanism (9) is in turn suspended by a traveling block (12) and wire rope (19) rigged from a crown block (not shown) located in the top of the drilling rig. The upper eyes (16) of the pair of bails (14) are hooked to the link supports (20) of the top drive (9), and the lower eyes (18) of the pair of bails (14) are hooked to the ears (22) protruding from the elevator (10). The bails (14) are secured to the elevator ears (22) by locking mechanisms (25) to prevent the bails (14) from inadvertently becoming uncoupled from the elevator (10). The elevator (10) and the supported tubular (24) are thus raised and lowered by the traveling block (12)/top drive (9) and bails (14). All the components in this series are designed to carry the expected loads.
The top drive (9) is used in place of a conventional rotary table and Kelly bushing to rotate the tubular during rotary drilling. Using hydraulic or electric motors (11) and a gear train (13) suspended above the drill string (24) enables the drill string to be rotated continuously while being lowered into or raised from a well. The top drive mechanism slides up and down along frame members (15) to check rotation of the top drive in reaction to the spinning of the tubular (24) while allowing free vertical movement of the device. Although a top drive mechanism (9) is shown in FIGS. 1-2, an elevator may alternatively be suspended directly from the traveling block (12) using links (14). In this case, the drilling platform is preferably equipped with a rotary table.
A spider, much like an elevator, is a device which holds a tubular to prevent it from descending into a well when it is not held by an elevator. Unlike an elevator, however, the spider is designed to remain on the drilling deck and is not moved vertically. When the elevator, connected to the traveling block, nears its high limit of travel (when raising a tubular) or its low limit or travel (when running a tubular), it must be repositioned in order to continue the operation. The spider holds the tubular prior to the elevator releasing the tubular. Thus, the tubular is held in place while the elevator is repositioned. Once the elevator holds the tubular at a new location, the spider is disengaged allowing the tubular to freely pass through the spider or for the spider to be moved completely clear of the tubular.
It is common practice to use a first elevator as a temporary substitute for a spider to support a tubular and a second elevator, coupled to the traveling block, to lower the tubular string. When the second traveling elevator is holding the tubular, the first elevator is moved clear of the tubular. The second elevator and tubular are lowered. When the second elevator has been lowered to the rig floor, the bails are removed from the second elevator and attached to the nearby first elevator. The second elevator now acts as the spider, while the first elevator is repositioned towards the top of the string where it is clamped to the tubular. The second elevator releases the tubular and is moved clear of the tubular, and the first elevator lowers the tubular into the well. When the first elevator reaches the rig floor, the elevators are again swapped in a process sometimes referred to as circulating the elevators. The same process is used in a reverse sequence for raising a tubular. Because both elevators change their location continuously during this process, there is no need for elevator/spider differentiation.
In the prior art, coupling the bails to the elevators is done in a time-consuming labor-intensive manual process. Extreme care must be taken when working with the heavy bails in order to avoid possibly severe injury to the rigger. Further, each bail must be securely fixed to the corresponding elevator ear, requiring another time-consuming step in the rigging process of manually engaging a locking device. A method to automate the repeated coupling, locking, unlocking, uncoupling of bails and elevators is desirable.
Further, many elevators used today employ powered internal mechanisms, e.g., power doors and/or power slips. When circulating the elevators, power and control lines to the elevators can interfere with deck operations, becoming entangled or snagging on objects. However, uncoupling and re-coupling supply and control lines is also a burdensome manual process, particularly if the elevator is hydraulically operated. A method which simplifies the supply of power to the elevators when circulating the elevators is desirable.
3. Identification of Objects of the Invention
A primary object of the invention is to provide a method and apparatus for increasing the efficiency of drilling operations by automating the process of connecting and locking bails or links to an elevator.
Another object of the invention is to provide a method and apparatus which prevents the need for riggers or other personnel to manually operate the bails or the elevator for coupling or uncoupling the two.
Another object of the invention is to provide a method and apparatus for providing power and control to a suspended elevator in a manner which does not cause power or control lines to hamper or otherwise interfere with deck operations.
Another object of the invention is to provide a method and apparatus for automatically coupling and uncoupling power and control lines to an elevator when the elevator is coupled or uncoupled to bails or links.
Another object of the invention is to promote operator safety by providing for total hands-free operation of the elevator.